ΔE 23.0, loose: different enough that you should pick on purpose. Hoeth Blue is noticeably lighter, much more saturated than Bismark's Grave.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Hoeth Blue is noticeably lighter, much more saturated than Bismark's Grave.
The same difference applies the other way round: Bismark's Grave is noticeably darker, much more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Bismark's Grave on the colour wheel See Hoeth Blue on the colour wheel
All matches: Bismark's Grave equivalents · Hoeth Blue equivalents